TITLE:   GCN CIRCULAR
NUMBER:  15391
SUBJECT: GRB 131024B: Mondy optical upper limits
DATE:    13/10/28 15:45:00 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

A.Volnova (IKI), E. Klunko (ISTP), M. Eselevich(ISTP), A. Pozanenko(IKI) 
report on behalf of larger GRB follow-up collaboration:

We observed the field of the Swift GRB 131024B (Krimm et al., GCN 15371) 
with AZT-33IK telescope of Sayan observatory (Mondy) starting Oct., 24 
(UT) 21:49:49, i.e. in ~14 minutes after the burst trigger. We obtained 
several images in R-filter with exposure of 30 and 60 seconds. Within 
the enhanced XRT circle (Beardmore et al., GCN 15374) we did not detect 
any optical counterpart.

The details of the photometry are the following:

UT start,   t-T0          Filter   Exp.  OT   UL (3 sigma)
            (mid, days)            (s)

21:49:49    0.02074       R       1860   n/d   21.8
21:49:49    0.03325       R       4020   n/d   22.5

The photometry is based 3 SDSS stars, R (gri -> R transformations by 
Lupton 2005):

SDSS id             R
J093757.56+441843.7 15.803
J093748.35+441919.6 17.774
J093744.86+441756.7 15.530